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linux/arch/x86/include/asm/percpu.h
Eric Dumazet 889a7a6a5d percpu, x86: Fix percpu_xchg_op() 
These recent percpu commits:

  2485b6464c: x86,percpu: Move out of place 64 bit ops into X86_64 section
  8270137a0d: cpuops: Use cmpxchg for xchg to avoid lock semantics

Caused this 'perf top' crash:

 Kernel panic - not syncing: Fatal exception in interrupt
 Pid: 0, comm: swapper Tainted: G     D
 2.6.38-rc2-00181-gef71723 #413 Call Trace: <IRQ> [<ffffffff810465b5>]
    ? panic
    ? kmsg_dump
    ? kmsg_dump
    ? oops_end
    ? no_context
    ? __bad_area_nosemaphore
    ? perf_output_begin
    ? bad_area_nosemaphore
    ? do_page_fault
    ? __task_pid_nr_ns
    ? perf_event_tid
    ? __perf_event_header__init_id
    ? validate_chain
    ? perf_output_sample
    ? trace_hardirqs_off
    ? page_fault
    ? irq_work_run
    ? update_process_times
    ? tick_sched_timer
    ? tick_sched_timer
    ? __run_hrtimer
    ? hrtimer_interrupt
    ? account_system_vtime
    ? smp_apic_timer_interrupt
    ? apic_timer_interrupt
 ...

Looking at assembly code, I found:

list = this_cpu_xchg(irq_work_list, NULL);

gives this wrong code : (gcc-4.1.2 cross compiler)

ffffffff810bc45e:
	mov    %gs:0xead0,%rax
	cmpxchg %rax,%gs:0xead0
	jne    ffffffff810bc45e <irq_work_run+0x3e>
	test   %rax,%rax
	je     ffffffff810bc4aa <irq_work_run+0x8a>

Tell gcc we dirty eax/rax register in percpu_xchg_op()

Compiler must use another register to store pxo_new__

We also dont need to reload percpu value after a jump,
since a 'failed' cmpxchg already updated eax/rax

Wrong generated code was :
	xor     %rax,%rax   /* load 0 into %rax */
1:	mov     %gs:0xead0,%rax
	cmpxchg %rax,%gs:0xead0
	jne     1b
	test    %rax,%rax

After patch :

	xor     %rdx,%rdx   /* load 0 into %rdx */
	mov     %gs:0xead0,%rax
1:	cmpxchg %rdx,%gs:0xead0
	jne     1b:
	test    %rax,%rax

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Tejun Heo <tj@kernel.org>
LKML-Reference: <1295973114.3588.312.camel@edumazet-laptop>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-01-26 08:10:49 +01:00

548 lines
18 KiB
C
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#ifndef _ASM_X86_PERCPU_H
#define _ASM_X86_PERCPU_H
#ifdef CONFIG_X86_64
#define __percpu_seg gs
#define __percpu_mov_op movq
#else
#define __percpu_seg fs
#define __percpu_mov_op movl
#endif
#ifdef __ASSEMBLY__
/*
* PER_CPU finds an address of a per-cpu variable.
*
* Args:
* var - variable name
* reg - 32bit register
*
* The resulting address is stored in the "reg" argument.
*
* Example:
* PER_CPU(cpu_gdt_descr, %ebx)
*/
#ifdef CONFIG_SMP
#define PER_CPU(var, reg) \
__percpu_mov_op %__percpu_seg:this_cpu_off, reg; \
lea var(reg), reg
#define PER_CPU_VAR(var) %__percpu_seg:var
#else /* ! SMP */
#define PER_CPU(var, reg) __percpu_mov_op $var, reg
#define PER_CPU_VAR(var) var
#endif /* SMP */
#ifdef CONFIG_X86_64_SMP
#define INIT_PER_CPU_VAR(var) init_per_cpu__##var
#else
#define INIT_PER_CPU_VAR(var) var
#endif
#else /* ...!ASSEMBLY */
#include <linux/kernel.h>
#include <linux/stringify.h>
#ifdef CONFIG_SMP
#define __percpu_arg(x) "%%"__stringify(__percpu_seg)":%P" #x
#define __my_cpu_offset percpu_read(this_cpu_off)
/*
* Compared to the generic __my_cpu_offset version, the following
* saves one instruction and avoids clobbering a temp register.
*/
#define __this_cpu_ptr(ptr) \
({ \
unsigned long tcp_ptr__; \
__verify_pcpu_ptr(ptr); \
asm volatile("add " __percpu_arg(1) ", %0" \
: "=r" (tcp_ptr__) \
: "m" (this_cpu_off), "0" (ptr)); \
(typeof(*(ptr)) __kernel __force *)tcp_ptr__; \
})
#else
#define __percpu_arg(x) "%P" #x
#endif
/*
* Initialized pointers to per-cpu variables needed for the boot
* processor need to use these macros to get the proper address
* offset from __per_cpu_load on SMP.
*
* There also must be an entry in vmlinux_64.lds.S
*/
#define DECLARE_INIT_PER_CPU(var) \
extern typeof(var) init_per_cpu_var(var)
#ifdef CONFIG_X86_64_SMP
#define init_per_cpu_var(var) init_per_cpu__##var
#else
#define init_per_cpu_var(var) var
#endif
/* For arch-specific code, we can use direct single-insn ops (they
* don't give an lvalue though). */
extern void __bad_percpu_size(void);
#define percpu_to_op(op, var, val) \
do { \
typedef typeof(var) pto_T__; \
if (0) { \
pto_T__ pto_tmp__; \
pto_tmp__ = (val); \
(void)pto_tmp__; \
} \
switch (sizeof(var)) { \
case 1: \
asm(op "b %1,"__percpu_arg(0) \
: "+m" (var) \
: "qi" ((pto_T__)(val))); \
break; \
case 2: \
asm(op "w %1,"__percpu_arg(0) \
: "+m" (var) \
: "ri" ((pto_T__)(val))); \
break; \
case 4: \
asm(op "l %1,"__percpu_arg(0) \
: "+m" (var) \
: "ri" ((pto_T__)(val))); \
break; \
case 8: \
asm(op "q %1,"__percpu_arg(0) \
: "+m" (var) \
: "re" ((pto_T__)(val))); \
break; \
default: __bad_percpu_size(); \
} \
} while (0)
/*
* Generate a percpu add to memory instruction and optimize code
* if one is added or subtracted.
*/
#define percpu_add_op(var, val) \
do { \
typedef typeof(var) pao_T__; \
const int pao_ID__ = (__builtin_constant_p(val) && \
((val) == 1 || (val) == -1)) ? (val) : 0; \
if (0) { \
pao_T__ pao_tmp__; \
pao_tmp__ = (val); \
(void)pao_tmp__; \
} \
switch (sizeof(var)) { \
case 1: \
if (pao_ID__ == 1) \
asm("incb "__percpu_arg(0) : "+m" (var)); \
else if (pao_ID__ == -1) \
asm("decb "__percpu_arg(0) : "+m" (var)); \
else \
asm("addb %1, "__percpu_arg(0) \
: "+m" (var) \
: "qi" ((pao_T__)(val))); \
break; \
case 2: \
if (pao_ID__ == 1) \
asm("incw "__percpu_arg(0) : "+m" (var)); \
else if (pao_ID__ == -1) \
asm("decw "__percpu_arg(0) : "+m" (var)); \
else \
asm("addw %1, "__percpu_arg(0) \
: "+m" (var) \
: "ri" ((pao_T__)(val))); \
break; \
case 4: \
if (pao_ID__ == 1) \
asm("incl "__percpu_arg(0) : "+m" (var)); \
else if (pao_ID__ == -1) \
asm("decl "__percpu_arg(0) : "+m" (var)); \
else \
asm("addl %1, "__percpu_arg(0) \
: "+m" (var) \
: "ri" ((pao_T__)(val))); \
break; \
case 8: \
if (pao_ID__ == 1) \
asm("incq "__percpu_arg(0) : "+m" (var)); \
else if (pao_ID__ == -1) \
asm("decq "__percpu_arg(0) : "+m" (var)); \
else \
asm("addq %1, "__percpu_arg(0) \
: "+m" (var) \
: "re" ((pao_T__)(val))); \
break; \
default: __bad_percpu_size(); \
} \
} while (0)
#define percpu_from_op(op, var, constraint) \
({ \
typeof(var) pfo_ret__; \
switch (sizeof(var)) { \
case 1: \
asm(op "b "__percpu_arg(1)",%0" \
: "=q" (pfo_ret__) \
: constraint); \
break; \
case 2: \
asm(op "w "__percpu_arg(1)",%0" \
: "=r" (pfo_ret__) \
: constraint); \
break; \
case 4: \
asm(op "l "__percpu_arg(1)",%0" \
: "=r" (pfo_ret__) \
: constraint); \
break; \
case 8: \
asm(op "q "__percpu_arg(1)",%0" \
: "=r" (pfo_ret__) \
: constraint); \
break; \
default: __bad_percpu_size(); \
} \
pfo_ret__; \
})
#define percpu_unary_op(op, var) \
({ \
switch (sizeof(var)) { \
case 1: \
asm(op "b "__percpu_arg(0) \
: "+m" (var)); \
break; \
case 2: \
asm(op "w "__percpu_arg(0) \
: "+m" (var)); \
break; \
case 4: \
asm(op "l "__percpu_arg(0) \
: "+m" (var)); \
break; \
case 8: \
asm(op "q "__percpu_arg(0) \
: "+m" (var)); \
break; \
default: __bad_percpu_size(); \
} \
})
/*
* Add return operation
*/
#define percpu_add_return_op(var, val) \
({ \
typeof(var) paro_ret__ = val; \
switch (sizeof(var)) { \
case 1: \
asm("xaddb %0, "__percpu_arg(1) \
: "+q" (paro_ret__), "+m" (var) \
: : "memory"); \
break; \
case 2: \
asm("xaddw %0, "__percpu_arg(1) \
: "+r" (paro_ret__), "+m" (var) \
: : "memory"); \
break; \
case 4: \
asm("xaddl %0, "__percpu_arg(1) \
: "+r" (paro_ret__), "+m" (var) \
: : "memory"); \
break; \
case 8: \
asm("xaddq %0, "__percpu_arg(1) \
: "+re" (paro_ret__), "+m" (var) \
: : "memory"); \
break; \
default: __bad_percpu_size(); \
} \
paro_ret__ += val; \
paro_ret__; \
})
/*
* xchg is implemented using cmpxchg without a lock prefix. xchg is
* expensive due to the implied lock prefix. The processor cannot prefetch
* cachelines if xchg is used.
*/
#define percpu_xchg_op(var, nval) \
({ \
typeof(var) pxo_ret__; \
typeof(var) pxo_new__ = (nval); \
switch (sizeof(var)) { \
case 1: \
asm("\n\tmov "__percpu_arg(1)",%%al" \
"\n1:\tcmpxchgb %2, "__percpu_arg(1) \
"\n\tjnz 1b" \
: "=&a" (pxo_ret__), "+m" (var) \
: "q" (pxo_new__) \
: "memory"); \
break; \
case 2: \
asm("\n\tmov "__percpu_arg(1)",%%ax" \
"\n1:\tcmpxchgw %2, "__percpu_arg(1) \
"\n\tjnz 1b" \
: "=&a" (pxo_ret__), "+m" (var) \
: "r" (pxo_new__) \
: "memory"); \
break; \
case 4: \
asm("\n\tmov "__percpu_arg(1)",%%eax" \
"\n1:\tcmpxchgl %2, "__percpu_arg(1) \
"\n\tjnz 1b" \
: "=&a" (pxo_ret__), "+m" (var) \
: "r" (pxo_new__) \
: "memory"); \
break; \
case 8: \
asm("\n\tmov "__percpu_arg(1)",%%rax" \
"\n1:\tcmpxchgq %2, "__percpu_arg(1) \
"\n\tjnz 1b" \
: "=&a" (pxo_ret__), "+m" (var) \
: "r" (pxo_new__) \
: "memory"); \
break; \
default: __bad_percpu_size(); \
} \
pxo_ret__; \
})
/*
* cmpxchg has no such implied lock semantics as a result it is much
* more efficient for cpu local operations.
*/
#define percpu_cmpxchg_op(var, oval, nval) \
({ \
typeof(var) pco_ret__; \
typeof(var) pco_old__ = (oval); \
typeof(var) pco_new__ = (nval); \
switch (sizeof(var)) { \
case 1: \
asm("cmpxchgb %2, "__percpu_arg(1) \
: "=a" (pco_ret__), "+m" (var) \
: "q" (pco_new__), "0" (pco_old__) \
: "memory"); \
break; \
case 2: \
asm("cmpxchgw %2, "__percpu_arg(1) \
: "=a" (pco_ret__), "+m" (var) \
: "r" (pco_new__), "0" (pco_old__) \
: "memory"); \
break; \
case 4: \
asm("cmpxchgl %2, "__percpu_arg(1) \
: "=a" (pco_ret__), "+m" (var) \
: "r" (pco_new__), "0" (pco_old__) \
: "memory"); \
break; \
case 8: \
asm("cmpxchgq %2, "__percpu_arg(1) \
: "=a" (pco_ret__), "+m" (var) \
: "r" (pco_new__), "0" (pco_old__) \
: "memory"); \
break; \
default: __bad_percpu_size(); \
} \
pco_ret__; \
})
/*
* percpu_read() makes gcc load the percpu variable every time it is
* accessed while percpu_read_stable() allows the value to be cached.
* percpu_read_stable() is more efficient and can be used if its value
* is guaranteed to be valid across cpus. The current users include
* get_current() and get_thread_info() both of which are actually
* per-thread variables implemented as per-cpu variables and thus
* stable for the duration of the respective task.
*/
#define percpu_read(var) percpu_from_op("mov", var, "m" (var))
#define percpu_read_stable(var) percpu_from_op("mov", var, "p" (&(var)))
#define percpu_write(var, val) percpu_to_op("mov", var, val)
#define percpu_add(var, val) percpu_add_op(var, val)
#define percpu_sub(var, val) percpu_add_op(var, -(val))
#define percpu_and(var, val) percpu_to_op("and", var, val)
#define percpu_or(var, val) percpu_to_op("or", var, val)
#define percpu_xor(var, val) percpu_to_op("xor", var, val)
#define percpu_inc(var) percpu_unary_op("inc", var)
#define __this_cpu_read_1(pcp) percpu_from_op("mov", (pcp), "m"(pcp))
#define __this_cpu_read_2(pcp) percpu_from_op("mov", (pcp), "m"(pcp))
#define __this_cpu_read_4(pcp) percpu_from_op("mov", (pcp), "m"(pcp))
#define __this_cpu_write_1(pcp, val) percpu_to_op("mov", (pcp), val)
#define __this_cpu_write_2(pcp, val) percpu_to_op("mov", (pcp), val)
#define __this_cpu_write_4(pcp, val) percpu_to_op("mov", (pcp), val)
#define __this_cpu_add_1(pcp, val) percpu_add_op((pcp), val)
#define __this_cpu_add_2(pcp, val) percpu_add_op((pcp), val)
#define __this_cpu_add_4(pcp, val) percpu_add_op((pcp), val)
#define __this_cpu_and_1(pcp, val) percpu_to_op("and", (pcp), val)
#define __this_cpu_and_2(pcp, val) percpu_to_op("and", (pcp), val)
#define __this_cpu_and_4(pcp, val) percpu_to_op("and", (pcp), val)
#define __this_cpu_or_1(pcp, val) percpu_to_op("or", (pcp), val)
#define __this_cpu_or_2(pcp, val) percpu_to_op("or", (pcp), val)
#define __this_cpu_or_4(pcp, val) percpu_to_op("or", (pcp), val)
#define __this_cpu_xor_1(pcp, val) percpu_to_op("xor", (pcp), val)
#define __this_cpu_xor_2(pcp, val) percpu_to_op("xor", (pcp), val)
#define __this_cpu_xor_4(pcp, val) percpu_to_op("xor", (pcp), val)
/*
* Generic fallback operations for __this_cpu_xchg_[1-4] are okay and much
* faster than an xchg with forced lock semantics.
*/
#define __this_cpu_xchg_8(pcp, nval) percpu_xchg_op(pcp, nval)
#define __this_cpu_cmpxchg_8(pcp, oval, nval) percpu_cmpxchg_op(pcp, oval, nval)
#define this_cpu_read_1(pcp) percpu_from_op("mov", (pcp), "m"(pcp))
#define this_cpu_read_2(pcp) percpu_from_op("mov", (pcp), "m"(pcp))
#define this_cpu_read_4(pcp) percpu_from_op("mov", (pcp), "m"(pcp))
#define this_cpu_write_1(pcp, val) percpu_to_op("mov", (pcp), val)
#define this_cpu_write_2(pcp, val) percpu_to_op("mov", (pcp), val)
#define this_cpu_write_4(pcp, val) percpu_to_op("mov", (pcp), val)
#define this_cpu_add_1(pcp, val) percpu_add_op((pcp), val)
#define this_cpu_add_2(pcp, val) percpu_add_op((pcp), val)
#define this_cpu_add_4(pcp, val) percpu_add_op((pcp), val)
#define this_cpu_and_1(pcp, val) percpu_to_op("and", (pcp), val)
#define this_cpu_and_2(pcp, val) percpu_to_op("and", (pcp), val)
#define this_cpu_and_4(pcp, val) percpu_to_op("and", (pcp), val)
#define this_cpu_or_1(pcp, val) percpu_to_op("or", (pcp), val)
#define this_cpu_or_2(pcp, val) percpu_to_op("or", (pcp), val)
#define this_cpu_or_4(pcp, val) percpu_to_op("or", (pcp), val)
#define this_cpu_xor_1(pcp, val) percpu_to_op("xor", (pcp), val)
#define this_cpu_xor_2(pcp, val) percpu_to_op("xor", (pcp), val)
#define this_cpu_xor_4(pcp, val) percpu_to_op("xor", (pcp), val)
#define this_cpu_xchg_1(pcp, nval) percpu_xchg_op(pcp, nval)
#define this_cpu_xchg_2(pcp, nval) percpu_xchg_op(pcp, nval)
#define this_cpu_xchg_4(pcp, nval) percpu_xchg_op(pcp, nval)
#define irqsafe_cpu_add_1(pcp, val) percpu_add_op((pcp), val)
#define irqsafe_cpu_add_2(pcp, val) percpu_add_op((pcp), val)
#define irqsafe_cpu_add_4(pcp, val) percpu_add_op((pcp), val)
#define irqsafe_cpu_and_1(pcp, val) percpu_to_op("and", (pcp), val)
#define irqsafe_cpu_and_2(pcp, val) percpu_to_op("and", (pcp), val)
#define irqsafe_cpu_and_4(pcp, val) percpu_to_op("and", (pcp), val)
#define irqsafe_cpu_or_1(pcp, val) percpu_to_op("or", (pcp), val)
#define irqsafe_cpu_or_2(pcp, val) percpu_to_op("or", (pcp), val)
#define irqsafe_cpu_or_4(pcp, val) percpu_to_op("or", (pcp), val)
#define irqsafe_cpu_xor_1(pcp, val) percpu_to_op("xor", (pcp), val)
#define irqsafe_cpu_xor_2(pcp, val) percpu_to_op("xor", (pcp), val)
#define irqsafe_cpu_xor_4(pcp, val) percpu_to_op("xor", (pcp), val)
#define irqsafe_cpu_xchg_1(pcp, nval) percpu_xchg_op(pcp, nval)
#define irqsafe_cpu_xchg_2(pcp, nval) percpu_xchg_op(pcp, nval)
#define irqsafe_cpu_xchg_4(pcp, nval) percpu_xchg_op(pcp, nval)
#ifndef CONFIG_M386
#define __this_cpu_add_return_1(pcp, val) percpu_add_return_op(pcp, val)
#define __this_cpu_add_return_2(pcp, val) percpu_add_return_op(pcp, val)
#define __this_cpu_add_return_4(pcp, val) percpu_add_return_op(pcp, val)
#define __this_cpu_cmpxchg_1(pcp, oval, nval) percpu_cmpxchg_op(pcp, oval, nval)
#define __this_cpu_cmpxchg_2(pcp, oval, nval) percpu_cmpxchg_op(pcp, oval, nval)
#define __this_cpu_cmpxchg_4(pcp, oval, nval) percpu_cmpxchg_op(pcp, oval, nval)
#define this_cpu_add_return_1(pcp, val) percpu_add_return_op(pcp, val)
#define this_cpu_add_return_2(pcp, val) percpu_add_return_op(pcp, val)
#define this_cpu_add_return_4(pcp, val) percpu_add_return_op(pcp, val)
#define this_cpu_cmpxchg_1(pcp, oval, nval) percpu_cmpxchg_op(pcp, oval, nval)
#define this_cpu_cmpxchg_2(pcp, oval, nval) percpu_cmpxchg_op(pcp, oval, nval)
#define this_cpu_cmpxchg_4(pcp, oval, nval) percpu_cmpxchg_op(pcp, oval, nval)
#define irqsafe_cpu_cmpxchg_1(pcp, oval, nval) percpu_cmpxchg_op(pcp, oval, nval)
#define irqsafe_cpu_cmpxchg_2(pcp, oval, nval) percpu_cmpxchg_op(pcp, oval, nval)
#define irqsafe_cpu_cmpxchg_4(pcp, oval, nval) percpu_cmpxchg_op(pcp, oval, nval)
#endif /* !CONFIG_M386 */
/*
* Per cpu atomic 64 bit operations are only available under 64 bit.
* 32 bit must fall back to generic operations.
*/
#ifdef CONFIG_X86_64
#define __this_cpu_read_8(pcp) percpu_from_op("mov", (pcp), "m"(pcp))
#define __this_cpu_write_8(pcp, val) percpu_to_op("mov", (pcp), val)
#define __this_cpu_add_8(pcp, val) percpu_add_op((pcp), val)
#define __this_cpu_and_8(pcp, val) percpu_to_op("and", (pcp), val)
#define __this_cpu_or_8(pcp, val) percpu_to_op("or", (pcp), val)
#define __this_cpu_xor_8(pcp, val) percpu_to_op("xor", (pcp), val)
#define __this_cpu_add_return_8(pcp, val) percpu_add_return_op(pcp, val)
#define this_cpu_read_8(pcp) percpu_from_op("mov", (pcp), "m"(pcp))
#define this_cpu_write_8(pcp, val) percpu_to_op("mov", (pcp), val)
#define this_cpu_add_8(pcp, val) percpu_add_op((pcp), val)
#define this_cpu_and_8(pcp, val) percpu_to_op("and", (pcp), val)
#define this_cpu_or_8(pcp, val) percpu_to_op("or", (pcp), val)
#define this_cpu_xor_8(pcp, val) percpu_to_op("xor", (pcp), val)
#define this_cpu_add_return_8(pcp, val) percpu_add_return_op(pcp, val)
#define this_cpu_xchg_8(pcp, nval) percpu_xchg_op(pcp, nval)
#define this_cpu_cmpxchg_8(pcp, oval, nval) percpu_cmpxchg_op(pcp, oval, nval)
#define irqsafe_cpu_add_8(pcp, val) percpu_add_op((pcp), val)
#define irqsafe_cpu_and_8(pcp, val) percpu_to_op("and", (pcp), val)
#define irqsafe_cpu_or_8(pcp, val) percpu_to_op("or", (pcp), val)
#define irqsafe_cpu_xor_8(pcp, val) percpu_to_op("xor", (pcp), val)
#define irqsafe_cpu_xchg_8(pcp, nval) percpu_xchg_op(pcp, nval)
#define irqsafe_cpu_cmpxchg_8(pcp, oval, nval) percpu_cmpxchg_op(pcp, oval, nval)
#endif
/* This is not atomic against other CPUs -- CPU preemption needs to be off */
#define x86_test_and_clear_bit_percpu(bit, var) \
({ \
int old__; \
asm volatile("btr %2,"__percpu_arg(1)"\n\tsbbl %0,%0" \
: "=r" (old__), "+m" (var) \
: "dIr" (bit)); \
old__; \
})
#include <asm-generic/percpu.h>
/* We can use this directly for local CPU (faster). */
DECLARE_PER_CPU(unsigned long, this_cpu_off);
#endif /* !__ASSEMBLY__ */
#ifdef CONFIG_SMP
/*
* Define the "EARLY_PER_CPU" macros. These are used for some per_cpu
* variables that are initialized and accessed before there are per_cpu
* areas allocated.
*/
#define DEFINE_EARLY_PER_CPU(_type, _name, _initvalue) \
DEFINE_PER_CPU(_type, _name) = _initvalue; \
__typeof__(_type) _name##_early_map[NR_CPUS] __initdata = \
{ [0 ... NR_CPUS-1] = _initvalue }; \
__typeof__(_type) *_name##_early_ptr __refdata = _name##_early_map
#define EXPORT_EARLY_PER_CPU_SYMBOL(_name) \
EXPORT_PER_CPU_SYMBOL(_name)
#define DECLARE_EARLY_PER_CPU(_type, _name) \
DECLARE_PER_CPU(_type, _name); \
extern __typeof__(_type) *_name##_early_ptr; \
extern __typeof__(_type) _name##_early_map[]
#define early_per_cpu_ptr(_name) (_name##_early_ptr)
#define early_per_cpu_map(_name, _idx) (_name##_early_map[_idx])
#define early_per_cpu(_name, _cpu) \
*(early_per_cpu_ptr(_name) ? \
&early_per_cpu_ptr(_name)[_cpu] : \
&per_cpu(_name, _cpu))
#else /* !CONFIG_SMP */
#define DEFINE_EARLY_PER_CPU(_type, _name, _initvalue) \
DEFINE_PER_CPU(_type, _name) = _initvalue
#define EXPORT_EARLY_PER_CPU_SYMBOL(_name) \
EXPORT_PER_CPU_SYMBOL(_name)
#define DECLARE_EARLY_PER_CPU(_type, _name) \
DECLARE_PER_CPU(_type, _name)
#define early_per_cpu(_name, _cpu) per_cpu(_name, _cpu)
#define early_per_cpu_ptr(_name) NULL
/* no early_per_cpu_map() */
#endif /* !CONFIG_SMP */
#endif /* _ASM_X86_PERCPU_H */
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